This application claims priority with respect to Japanese Application No. 2001-126463, filed Apr. 24, 2001.
The present invention relates to an apparatus for changing operational plate cylinders during rotary press operation in a rotary press. The rotary press includes at least two or more plate cylinders, drive means for driving the plate cylinders and switching means for selectively switching the plate cylinders in a printable state and in an unprintable state.
A rotary press is publicly known as to have switching means for selectively switching plate cylinders in a printable state and in an unprintable state as disclosed in the publication of JP 8-207233A entitled xe2x80x9cRoll Rotary Pressxe2x80x9d (hereinafter referred to as the prior art).
In the above prior art, the rotary press comprises at least one paper feeder for feeding a web paper, printing units provided with a plurality of plate cylinders, and a folding unit for cutting and folding the web paper after printed. In such the arrangement, the printing units and the folding unit are driven from respective individual drive means.
The web paper drawn from the paper feeder is passed through the printing units for use in printing from now on, including one that contains a plate cylinder in an unprintable state, and is transported to the folding unit, followed by print operation running. After prints are completed for an appropriately set print count, the printing unit being in the unprintable state by halting the plate cylinder is activated and accelerated to have a match in terms of a print operation speed and phase of the rotary press during operation.
The plate cylinder of the printing unit in the unprintable state, of which plate surface is separated from the surface of the web paper, is switched into the printable state, of which plate surface is contacted with the surface of the web paper, to start printing. On the other hand, as for the printing units previously designated appropriately before printing among the printing units in operation, their plate cylinders are switched from the printable state to the unprintable state, decelerated and halted. As described above, the prior art shows a rotary press that can change images to be printed without halting the rotary press during operation.
The above prior art, however, has some subject matters that should be solved respectively. In the prior art, although, in order to change operational plate cylinders, the plate cylinder halted in the unprintable state is activated and accelerated so as to have a match to the operation print speed of the rotary press, a timing of activation is not shown at all. In the print operation, the print count is previously determined for each printing. Therefore, it is desired to perform a production with a necessary and minimum print count before change of print operational plate cylinders to minimize undesired recording paper (paper loss). In practice, however, a system is not established for changing print operational plate cylinders at timing appropriate for actual prints that are not less than a scheduled print count. Accordingly, it is intended to determine an actual print count slightly larger, resulting in a trend of elevating the undesired recording paper (paper loss), which leads to cost up.
The present invention is intended to solve such the subject mattes at a stroke that involve the prior art. It is therefore an object of the present invention to provide an apparatus for changing operational plate cylinders during rotary press operation, which is possible to substantially equalize an actual print count to a set print count before change of operational plate cylinders. This can eliminate waste to print the undesired recording paper (paper loss) and lead to cost down.
To achieve the above object, the present invention provides an apparatus for changing operational plate cylinders during rotary press operation in a rotary press. The rotary press includes at least two or more plate cylinders, drive means for driving the plate cylinders and switching means for selectively switching the plate cylinders in a printable state and in an unprintable state. The apparatus comprises input console means available for designating an earlier operational plate cylinder that is switched from the printable state to the unprintable state by the switching means and a later operational plate cylinder that is switched from the unprintable state to the printable state by the switching means among the two or more plate cylinders, setting at least a print count before change of operational plate cylinders, and inputting a print operation command to the rotary press; drive control means for performing a normal control for controlling the drive means to rotate the plate cylinder with a match in terms of a reference rotational speed and phase, and performing a special control for controlling the drive means to accelerate the later operational plate cylinder in a halt state up to a rotational speed in coincident with the same rotational speed as that of another plate cylinder normally controlled; drive signal output means for providing the drive control means with a normal control signal indicative of executing the normal control and a special control signal indicative of executing the special control; print count management means for always checking a print operation speed of the rotary press and an actual print count of a print operation; and switching signal output means for providing the switching means with a switching signal indicative of switching the earlier operational plate cylinder and a switching signal indicative of switching the later operational plate cylinder. The print count management means is configured to compute a print count printed at the print operation speed by the plate cylinder in printing operation under the normal control during a preset time period to specially control the drive means for the later operational plate cylinder. The drive signal output means is configured to output the normal control signal indicative of executing the normal control for other plate cylinders than the later operational plate cylinder based on the print operation command, to output the special control signal indicative of executing the special control for the later operational plate cylinder when the actual print count checked at the print count management means reaches a value obtained by subscribing a sum of the computed value and a preset constant from a print count before change of operational plate cylinders set by the input console means, and to output the normal control signal indicative of executing the normal control for the later operational plate cylinder when the later operational plate cylinder has a rotational speed matched to that of the another plate cylinder normally controlled after the later operational plate cylinder is specially controlled for the preset time period. The drive signal output means is configured to provide the switching means with the switching signal when the later operational plate cylinder has a rotational phase matched to the reference rotational phase under the normal control and the actual print count checked by the print count management means reaches a print count before change of operational plate cylinders set by the input console means.
In accordance with the apparatus for changing operational plate cylinders during rotary press operation according to the present invention, an operational plate cylinder can be changed immediately after completion of printing for the set print count before change of the operational plate cylinders without halting print operation.